RQM - CTD Data From the Coriolis Concerted Mission (MAC2021): Odyssée Saint-Laurent 2021

The September 2021 concerted mission, funded by the St. Lawrence Odyssey program of the Réseau Québec maritime (RQM), aimed to address the lack of knowledge about contaminants, phytoplankton and benthic communities, and the adaptation of organisms to environmental and anthropogenic changes in the St. Lawrence system. This mission enabled extensive data acquisition for 8 research projects, largely focused on the sampling and analysis of benthic invertebrates along the oxygen gradient of the St. Lawrence system, and on the sampling of marine fungi by developing a new methodology combining sediment sampling buckets and the use of zooplankton nets.

Vertical profiles of CTD data (conductivity, temperature, depth) were made in the water column at 55 stations between the mouth of the Saguenay River and the Magdalen Islands in the Gulf of St. Lawrence. These profiles were taken from the surface (from a depth of 1 m) to a maximum of 6 m from the seabed. They include measurements of temperature, salinity, density, pH, fluorescence, dissolved oxygen, light transmission, vertical stratification and sound velocity in seawater. Discrete water samples were collected at different stations and depths to compare CTD's direct measurements with laboratory analyses of dissolved oxygen concentration (20 samples, Winkler chemical titration), and salinity (30 samples). These comparisons were used to adjust the calibration of dissolved oxygen and salinity data from the CTD.